Biventricular Pacing for Atrioventricular Block and Systolic Dysfunction
What is the impact of biventricular pacing on mortality, morbidity, and adverse left ventricular (LV) remodeling in patients with atrioventricular (AV) block and heart failure?
The investigators enrolled patients who had indications for pacing with AV block; New York Heart Association (NYHA) class I, II, or III heart failure; and a LV ejection fraction of ≤50%. Patients received a cardiac-resynchronization pacemaker or implantable cardioverter-defibrillator (ICD) (the latter if the patient had an indication for defibrillation therapy) and were randomly assigned to standard right ventricular (RV) pacing or biventricular pacing. The primary outcome was the time to death from any cause, an urgent care visit for heart failure that required intravenous therapy, or a 15% or more increase in the LV end-systolic volume index. Kaplan–Meier curves were generated for each outcome in each of the study groups.
Of 918 patients enrolled, 691 underwent randomization and were followed for an average of 37 months. The primary outcome occurred in 190 of 342 patients (55.6%) in the RV pacing group, as compared with 160 of 349 (45.8%) in the biventricular pacing group. Patients randomly assigned to biventricular pacing had a significantly lower incidence of the primary outcome over time than did those assigned to RV pacing (hazard ratio, 0.74; 95% confidence interval, 0.60-0.90); results were similar in the pacemaker and ICD groups. LV lead-related complications occurred in 6.4% of patients.
The authors concluded that biventricular pacing was superior to conventional RV pacing in patients with AV block and LV systolic dysfunction.
This study suggests that biventricular pacing provides superior ventricular rate support, as compared with traditional RV apical pacing, in patients with AV block, mild-to-moderate heart failure, and abnormal LV systolic function. Patients receiving biventricular pacing had a lower incidence of the primary outcome of an urgent care visit for heart failure, death from any cause, or progression of heart failure, as measured by a significant increase in the LV end-systolic volume index. This study adds to the existing body of evidence suggesting that biventricular pacing in patients with AV block appears to preserve systolic function.
Keywords: Atrioventricular Block, Defibrillators, Cardiac Pacing, Artificial, Heart Failure, Ventricular Remodeling, Pacemaker, Artificial
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